dan rivers is cover the story in london. i asked him how active these vigilante groups are. >> reporter: those doing these patrols are reveling in the media spotlight. actually the number of people involved is very, very small. five have been arrested on suspicion of harassment. these men claim they're simply tackling drunken behavior, where alcohol is already banned from the streets. but britain isn't the only country struggling to contain such behavior. in denmark, an islamist from another so-called muslim patrol stands menacingly outside a polling station, vowing to stop muslims voting. in belgium, extremists want existing sharia courts which handle family matters to cover criminal matters in muslim areas. in spain, hard-line groups have angered locals by demanding pet dogs are banned from public transport and muslim neighborhoods, leading british muslims have but there is evidence that the lack of integration is partly because, in many cities across europe, white people are moving away from ethnically mixed neighborhoods